Steam generator



c. w. HASEK, .13., EIAL 2,924,204

Feb. 9, 1960 STEAMYGENERATOR 3 Sheets-Sheet 2 Filed Sept.'21, 1956mmvmns Carl W. HasekJR Everefr A. Caflin ATTORNEY Feb. 9, 1960 c. w.HASEK, JR. EI'AL STEAM GENERATOR 3 Sheets-Sheet 3 Filed Sept. 21. 1966uvmvroxs Carl W. HasekJR BY Ev'erefi A. Carlin AT TORNEY United States2,924,204 Patented Feb. 9, 1960 STEAM GENERATOR This invention relatesto a fluid heating apparatus and more particularly to an improved vaporgenerator having a liquid-vapor separating drum provided with novelmeans for channeling vapor-liquid mixtures of different qualitiesthereinto and separating said mixtures into their consistent parts bygravitational means.

An object of this invention is to provide in a vapor generator animproved vapor separating means. whereby the efliciency of theseparation of the liquid-vapor mixtures i.e. vapor dryness is materiallyincreased in a relatively simple, effective, and inexpensive manner.

Another object of this invention is to provide in an improved vaporgenerator a natural flow circulating arrangement resulting in anincreased circulating head for a given heat input.

The objects and advantages of this invention are accomplished by a vaporgenerator having in a setting, a furnace, an associated convection gaspass and a boiler unit, the latter including an upper liquid-vaporseparating drum having therein an improved liquid-vapor mixtureseparating means, a lower drum and connecting generating tubes. Thegenerating tubes include a group of high duty, vapor generating tubesdisposed adjacent, lining or forming a part of the walls of the furnace,the tubes being subjected to the highly heated combustion gases forgenerating a low-density, liquid-vapor mixture, i.e. a mixture having ahigh percentage of vapor by weight; a group of lower duty generatingtubes disposed in the forward end or hot portion of the convection gaspass generating a higher density mixture, i.e. one having a lowerpercentage of vapor by weight and a group of downcomer tubes disposedrearwardly of thelow duty tubesin the cooler portion of the gasconvection pass.

According to this invention, the vapor-liquid separating drum isprovided with means forming a liquid compartment and a plurality ofdistinct, juxtaposed, circumferentially disposed compartments adjacent awall portion of the drum, the juxtaposed compartments being arranged soas to receive respectively the discharge ends of the high dutygenerating tubes and the discharge ends of the low duty tubes. Thus thelow density mixture of the high duty tubes are collected in onecompartment and the high density mixture emanating from the low dutytubes collected in another compartment. Each of the compartmentsadjacent the upper end thereof is provided with means forming adischarge port through which the respective vapor-liquid mixtures aredischarged, the discharge ports being in communication with the spaceabove the level of the liquid. The discharge ports of the respectivemixture receiving compartments are spaced one above the other with thehigh velocity, low density mixture emanating from the higher port.Further the [ports are arranged to discharge flow of the mixturesstreaming out of the respective receiving compartments in a laterally,outwardly converging direction to affect gravitational separation of theliquid from the vapor in -the space above the liquid livel. The liquidthus sepa rated from the vapor is collected in the liquid compartmentand the vapor separated from the liquid iscollected in the space abovethe liquid. As a result the liquid standing in the liquid compartment issubstantially solid, i.e. free of entrained vapor, thereby allowingsubstantially solid liquid to flow through the downcomers.

Therefore, the fluid flowing through the downcomer has a minimumspecific volume resulting in a minimurn re striction to flow. The effectis to increase the weight of liquid circulated to a maximum for adesired operating condition 'whereby the heat absorption per poundoffluid flowing in the downcomers is'minimized, Consequently for a givenheat input, the velocity of the fluid in the downcomers is increasedresulting in a greater circulating head on the vapor generator. Toachieve desired results the discharge ports of the mixture receivingcompartments are proportioned to discharge the fluid mixture'flowingoutwardly therefrom at predetermined relative velocities to insuregravitational separation of the mixture into its constituent parts andto maintain the pressure drop through the port opening low enough so asto not impede the fluid circulation of the system. 7

A feature of this invention resides in the provision of an improvedvapor and liquid separating drum having means for deflecting or changingthe directional flow of the respective liquid-vapor mixtures as thelatter aredischarged outwardly from juxtaposed, mixture receivingcompartments for affecting an improved gravitational separation of themixtures into its constituent parts, whereby the liquid because of itsgreater weight gravitates to the liquid compartment. 7

Another feature of this invention resides'in the provision of animproved vapor and liquid separating drum having means for dischargingliquidvapor mixtures of different quality out of juxtaposed, mixturereceiving compartments at relative velocities so as to prevent carryoverof the liquid separating from the vapor of the low density mixturedischarging outwardly from one compartment by the vapor separating fromthe liquid of a high density mixture which is flowing out from thejuxtaposed compartment.

Still another feature of this invention resides in. the provision thattheseparation of the mixtures into its constituent parts bygravitational means above the normal liquid level of the drum eliminatesundesirable fiuxation in the level of the liquid within the drum. 7 A

Otherfeatures and advantages will be readily apparent when considered inview of the drawings and accompanying description in which:

Fig. 1 is a front elevation sectional view of a vapor generatorincluding a furnace with walls defined by vapor generating tubes and atwo drum vapor generating convec'tion section heated by gases from thefurnace,

Fig. 2 is a detailed longitudinal sectional view having portions thereofbroken away of an improved vapor and liquid sparating drum according tothis invention,

Fig. 3 is a left end sectional view of the drum taken along line 33 ofFig. 2,

Fig. 4 is a right end sectional view of the drum taken along line 44 ofFig. 2,

Fig. 5 is an intermediate sectional view of the drum taken along line 55of Fig. 2.

1 While the instant invention is directed to vapor generator generally,for the purpose of illustration and description, particular reference ismade to a steam generator having particular utility as a marine boiler.Referring to Fig. l, the steam generator according to this inventionconsists of a setting 10 comprising a furnace cavity 11 fired bysuitable burners 12 and an associated gas convection pass 13. Housedwithin this'setting'ltl are the pressure parts of the boiler unit.

steam and water drum 14, which according to this invention and as willbe hereinafter described is provided with means for improving thequality of steam separation, i.e. steamdryness, as well as for affectingan increase in the circulatin'g head on the boiler unit; a lower liquidor water driim15 anda plurality of vapor or steam generating tubes incommunication with the upper and lower drum'sr" According tothisinvention the vapor generating tubeSare made'up of a groupofhigh-duty tubes 16 andagroupof low duty tubes 17. a

t The high duty vapor or steam generating tubes 16 consist ar a bank ofstaggered screen tubes 16A extending from-front to rear of the settingand separatesthe furnace cavity 11 from the convection gas pass 13, thescreen tubes 1 6A being directly connected to drums 14 and 15. Includedalso as high'duty-tubes are the furnace wall tubes, which as shownincludea group of furnace rear-wall-tubes 16B, furnace sidewall tubes16C and roof tubes 16D, the latter forming a continuation of the sidewall tubes1'6C. The furnace rear wall riser tubes 16B lead u'p wardlyfrom a rear wall lower header 18, the latter being connected to thewater drum 15 by tubes 19, and-connect intoan upper rear wall header 20which is appropriately connected to the main steam drum 14 by aseries'of tubes 16E. If desired, the upper header 20 is providedwithsuitable diaphragms (not shown) to protvide-a plurality of compartmentsfrom which a plurality of outlet tubes-16E discharge a steam-watermixture to longitudinal spaced positions along the drum 14. The sidewallriser .tubes 16C lead upwardly from alower sidewall head 21 which isconnected to the water drum 15*by-a seriesof tubes .22, the upperportions of. the sidewall tubes 16C being bent to follow the slope ofthe roof portion 23 of the setting and have the discharge ends thereofconnected directly to the steam drum 14.

According to this invention the low duty group of vapor or steamgenerating tubes 17 are disposed in the gas convection pass 13, i.e. tothe left of the screen tubes 16Aas viewed in Fig. 1, and spacedtherefrom to provide a setting for a bank of superheater tubes 24disposed in "thespace therebetween. As shown the low duty tubes 17'consist of a ten row, inclined bank of tubes which i are directlyconnected to the drums 14 and 15.

To the left of the low duty tubes 17and disposed in the cooler portionof the gas convection pass 13 is a bank of inclined downcomer tubes 25connecting the main steam drum14 to the lower water drum 15; the bank ofdowncomers consisting often rows of tubes extending across the setting.i

t According to this invention the main steam drum 14 is provided withpartitioning means 26 and 27 extending substantially the length of thedrum dividing the same into a liquid or water space or compartment 28and into a plurality of distinct and separate, juxtaposed,circumferentially extending compartments 29 and 30, the lattercompartments 29 and 30 forming independent outlet manifolds forreceiving the mixture of steam and water formed in the high duty and lowduty generating tubes 16 and17 respectively.

Referringzparticularly to Figs. 2 to 5, the improved 7 adjacent wallportion 15A of the drum-andcQ-operates 1 therewith to form the manifoldcompartments 29 which As shown, two manifold compartments are formedbetween a pair of end plates 34 and 35 connected to the interior wallsurface of the drum adjacent the ends thereof and extend inwardlytherefrom a distance equal to approximately 25 percent of the diameterof the drum.

Connected to and extending therebetween are a pair of. spaced partitionmeans 26: and 27, shown diagrammaticah eral plate sectionswhich aresupported in a line extending substantially the length of the drum byintermediate supporting plates 36 longitudinally spaced between the andsupport plates 34 and 35.

As shown in Figs. Z'and 5, partition means 26 includes a plurality ofplate sections 26A, 26B, 26C and 26D connected by suitable means, suchas bolts 26Eand the like. It is to be noted that the plates 26A-D aretied together in a manner to simulate the curvature ofy the terminate inan upwardly diverted opening 37. 'If desired the intermediate supportplates36 are providedwith a cutout notch 36Ato provide means wherebyeachsectionof the manifold compartment may be rendered in communicationwith each other -A second partition means-27 spaced from partition '26 1and connected to a projected portion 34A,1'35A ofthe support plates 34,35 respectively form therewith a second manifold compartment; The secondpartition 27 likewise is made-up of. a plurality of plate sections271M273, and 27C which are disposed in spaced relationship'tothe plates26AD of partition 26 to form therewith the second manifold compartment30.. As shown in Figsal and 1 5 the second compartment30 terminates inan opening 38' a which is spaced below that of the opening 37 ofcomsteam drum 15 of this invention consists of a closed end cylindricalshell .31 having internally disposed along the top thereof a perforatedsteam 'pipe' 32, Figs. 3 to 5, which communicates with the steam outlet33. To divide the interior of the drum into a water compartment 28 andinto a plurality of separate and distinct. manifoldcompartmentsextending substantially the length of the drum, suitabledividing means such as haffles and/or partitioning plates are utilizedwhich co-operate with the walls of the drum and with each other to formthe distinct compartments. While the partitioning means 26 and 27 may beintegrally formed, in the illustrated'form of the .invention the saidmeans are formed of severalseparately connected plate members;

partment 29. As noted from Fig. 1,-both openings are "disposed above thenormal level of the waterfin'thewater 1 compartment 28, thelatter beingformed between the;

second described partition 27 and the opposite wall 39 0f the drum'15. K

According to this invention baffle means '40 and 41 spaced above theopenings 37and 38,*respectively,' are provided to form therewithdischarge ports 42, 43 through which a liquid and vapor mixture isadapted to be discharged outwardly from the respective compartments asit will be hereinafter described. As shown the upper bafile means 40consist of aplate disposed between the steam dry pipe 32 and opening 37and is sealed welded to the drum to incline downwardly and inwardly toform the discharge port 42,'the inner 'end of the bathe being providedwith an upturned flange 40A. Spaced there.- from and connected toplatesections 26A and projecting substantially perpendicular thereto(i.e. "extending in a.

substantially horizontal direction-substantially parallel.

to the liquid level) is a secondbaffie means 41spaced above opening 38and forming therewith the discharge port 43 ofthe secon'dcompartment.

As best seen in Fig. 1 it will be n'oted that the high duty tubes 16,i.e.the screendhbes 16A, roof tube's16D and tubes 16E have theirdischarge ends incommhnication with compartment; 29. The-lower dutytubes'g17 discharge into thesecond compartment 30 and the downcomers25connect thewatercompartment 28 with the Thus in operation with theburners- 12" firing in the furnace cavity, the screen tubes, 16Ayandfurnace wall tubes 16B, 16CIandfI6D- exposed to the hot gases ofcombustion become' highly heated thereby "and generate a predominentportion of the steam ofgthe unit which is dischargedinto compartment 29as a low density mix-.

ture of steam and *water at.relatively.high velocities.

:. As thegases flowthrough the convection pass 13, the.lower,.duty...tube's 17. become h ated- ,1 Howeve 93% 'of-the heat ofthe gases has already been absorbed by the superheater 24 etc., thesetubes do not absorb as much heat as the screen and furnace wall tubesand therefore the amount of steam generated therein is less.Accordingly, the ratio of steam to water in tubes 16 is greater than theratio of steam to water in tubes 17, the latter discharging into thesecond compartment 30 at a comparative lower velocity thanthat of themixture discharging into compartment 29. As indicated in Figs. 1 and 5,the high ratio and low ratio steam and water mixtures stream into itsseparate compartment 29, 3t) and is deflected outwardly therefromthrough the ports 42, 43 by the baflles 40 and 41 respectively. Bychanging the direction of flow as the mixtures are discharged and due tothe greater weight of the water, a gravitational separation of themixture occurs. According to the invention, it had been discovered thatby diverting the mixture having the higher velocity downwardly, asindicated by the arrows in Figs. 2 and 5, entrainment of the water bythe steam as the latter rises to seek the steam outlet 33 issubstantially eliminated.

The mixture discharging from the compartment 30 has a relative lowervelocity and gravity effectively separates this mixture into its liquidand vapor parts. By properly proportioning of the port openings 42 and43, the velocities of both mixtures can be controlled so that the waterseparating from. the mixture of the higher port 42 will not be entrainedor carried over by the vapor separating from the mixture dischargingfrom the lower port 43.

It will be further noted that the improved drum arrangement hereindiscussed provides for an improved boiler circulation. Because themixtures from the high duty and low duty tubes are discharged intoseparate and distinct compartments and separated above the normal waterlevel, the water standing in the drum is substantially solid. For thisreason, the water flows through the downcomer 25 substantially free ofany entrained vapor. Therefore, since the water flowing through thedowncomer has a minimum specific volume, the weight of water circulatedis greater and the heat absorbed per pound of water flowing in thedowncomer is reduced. Thus as the velocity of the water in the downcomeris increased, the circulating head on the boiler is increased. Tomaintain this advantage the ports 42 and 43 are proportioned to maintainthe pressure drop through the port opening sufficiently low so as to notimpede this circulation.

It will be further noted that the improved arrangement of this inventioneliminates fluxation of the water level within the drum in that thespecific volume of the water is maintained at an absolute minimum sinceit is substantially free of vapor.

Further, it will be apparent that the instant invention provides meansfor affecting an improved quality of steam separation in a relativelysimple, efiicient and expedient manner, while at the time provides anincreased circulating head for the boiler.

While the instant invention has been disclosed in accordance to aparticular embodiment thereof, it is to be appreciated that theinvention is not to be taken as limited to all of the details thereof asmodifications and variations thereof may be made without departing fromthe spirit or scope of the invention.

What is claimed is:

1. In a vapor generator, a vapor liquid separting drum normally having aliquid level therein separating a liquid space from a vapor space andnormally having a high density and low density liquid vapor mixturesimultaneously discharged thereinto, a dry vapor pipe within the drumextending longitudinally along the top thereof, gravity means forseparating each of said mixtures into its respective vapor and liquidconstituents, said gravity separating means including a first partitionspaced from a circumferential wall portion of the drum and forming 6therewith a circumferentially extending compartment adapted to enclosethe ends of generating'tubes discharg ing the low density liquid-vapormixture into said drum,

' said compartment having an upper open end above the liquid level, asecond partition spaced from said first partition and forming therewitha second compartment adapted to enclose the ends of generating tubes.discharging the high density liquid-vapor mixture into said drum, saidsecond compartment having. an open upper end positioned above the liquidlevel and below the open upper end of said first compartment, a firstdownwardly inclined bafile means positioned between the dry pipe and theupper open end of said first compartment, said baffie means co-operatingwith said open end of said first compartment to form therewith adischarge port, a second substantially horizontally disposed bafilemeans connected to said first partition, said second bafile means beingspaced above the opening of said second compartment and forms therewiththe discharge port of said second compartment, the port of said firstcompartment being disposed above the port of said second compartment,said ports discharging the liquid-vapor mixtures of their respectivecompartments into the free vapor space above the liquid level, saidfirst bafiie means directing the low density liquid-vapor mixtureemanating from said first compartment angularly downwardly towards theliquid level and said second bafile means directing the high densitymixture emanating from said second compartment in a directionsubstantially parallel to the liquid level at a position above theliquid level and below the discharge port of the low density mixturewhereby said high density liquid-vapor mixture discharging substantiallyparallel to the liquid level blankets the downwardly directed lowdensity mixture from direct impingement on said liquid level, saidblanketing effect enhancing the dryness of the separating vapor byminimizing foaming and moisture carry-over due to direct impingement ofthe separating vapors of the respective mixtures on the liquid level.

2. In a vapor generator, a vapor liquid separating drum normally havinga liquid level therein separating a liquid space from a vapor space andnormally having a high density and low density liquid vapor mixturesimultaneously discharged thereinto, means forming a steam outlet at thetop of said drum, gravity means for seperating each of said mixturesinto its respective vapor and liquid constituents, said gravityseparating means including a first partition spaced from acircumferential wall portion of the drum and forming therewith acircumferentially extending compartment adapted to enclose the ends ofgenerating tubes discharging the low density liquid-vapor mixture intosaid drum, said compartment having an upper open end above the liquidlevel, a second partition spaced from said first partition and formingtherewith a second compartment adapted to enclose the ends of generatingtubes discharging the high density liquid vapor mixture into said drum,said second compartment having an open upper end positioned above theliquid level and below the open upper end of said first compartment, afirst downwardly inclined bafile means positioned between said steamoutlet means and the upper open end of said first compartment, saidbaffle means co-operating with said open end of said first compartmentto form therewith a discharge port, a second substantially horizontallydisposed bafile means connected to said first partition, said secondbafiie means being spaced above the opening of said second compartmentand forms therewith the discharge port of said second compartment, theport of said-first compartment being disposed above the port of saidsecond compartment, said-ports discharging the liquid-vapor mixtures oftheir respective compartments into the free vapor space above the liquidlevel, said first bafile means directing the low density liquid-vapormixture emanating from said first compartment angularly downwardlytowards thq liquid level a nd said second baffle. means dire qing thq]high density Tmixtiire emanating; from said sabnd dqnipar tm'ent in adirection substantially parallel to the nli zing foaming moisturecarry-over due to direct

